The invention relates to a device and a process for the separation of solids from a fluid or for the separation of sediments which have precipitated out of emulsions by means of a band filter, a mixing device, and equipment for the metered addition of mixtures of chemicals.
Such a device, which may also be transportable, and which is used for processing used emulsions or industrial wastes, if these emulsions have been separated with suitable chemicals and the sediment has been separated from the fluid which is usually water, is described in European Patent No. 0 067 959. That device comprises a reaction container in which the wastes to be processed are held, and in which mixing devices or stirring mechanisms are located in order to thoroughly mix the mixture of chemicals with the wastes, an adjoining flocculation container in which the wastes which have been mixed with the mixture of chemicals are held while the separating reactions proceed and in which the flocculation which is forming can be precipitated, and a filter belt through which the waste liquids which have remained with the sediment flow into a filtrate collection tank with the sediment remaining behind on the filter belt.
This device is useful and valuable for purifying wastes. However, it has the disadvantage due to the various containers which are needed, that it requires a relatively large surface area, and it is not very practical for smaller operations or for limited spaces which have an output which remains constant.
In the older but later published German Patent Application No. P 38 42 557, an analogous process for the processing of industrial wastes and emulsions is described in which a more compact manner of construction is attained by encompassing a cylinder drum with a filter device. The drum is positioned in a supported manner in a curve of a continuous conveyor belt comprising individual elements connected in an articulated manner which are set into rotation. A filter belt of non-woven fabric is moved forward between the cylinder drum casing and the conveyor belt, and the cylinder drum has openings. The sediment forming in the cylinder drum is removed from the cylinder drum and transferred onto the conveyor belt to be discharged from the device along with the used filter belt.
In this device a more compact construction is achieved because only the reaction container is still positioned separately and next to the filter device. The residence time is spent in a flocculation container which also contains the cylinder drum with the filter belt. Therefore, an additional container in which the fluid must reside for a specific time can be eliminated.
It is thus the task of the present invention to achieve a further compaction of such a device as has already been described, by dispensing with a separate mixing container and reaction container, whereby the device essentially contains only one container to perform both functions. Accordingly, the device becomes highly adaptable and can be accommodated within the smallest spaces, and it has a relatively high throughput capacity so that additional industrial operations are afforded the possibility for regular and timely waste purification.
In accordance with the invention the mixing container in which the wastes to be purified or processed are mixed with the chemical mixture and the container for accommodating the residence time for chemical reaction between the chemical mixture and the wastes are combined and located within a rotating cylinder drum. The drum has a casing surface which has at least one, and preferably two openings positioned diametrically opposed to one another. The drum is set into rotary motion by a motor driven continuous jointed belt conveyor, the cylinder drum being positioned within a curve of the belt conveyor. A filter belt, preferably one of a non-woven fabric, has a width which corresponds to the width of the cylinder drum casing and the jointed belt conveyor. At the discharge end where the jointed belt conveyor separates from the casing surface of the cylinder drum, the filter belt is conducted under a pressing roller, and is finally discarded. The sediment located on the filter belt is thereby pressed and dewatered. The cylinder drum preferably only rotates in stages over short distances, but it can also rotate slowly and continuously. The rotation speed can be regulated and is determined by the type of filtration process or by the type of the wastes which are to be processed.
It will now be appreciated that the cylinder drum, which has a casing which is provided with openings on at least one point, forms either a reaction container or a container for the residing fluid. This fluid is mixed with the chemicals and the cylinder drum is filled to approximately one third of its diameter or more. Within the interior of the cylinder drum, a mixing turbine is attached on a projecting arm which projects through a lateral opening. This projecting arm also serves as a feed for the mixture of the chemicals which are provided for the separation of the emulsions. A device for monitoring the level of the fluid is also located within the interior of the cylinder drum and attached to the projecting arm. The cylinder drum preferably has two openings positioned opposite one another in the casing. The size of these openings is dependent on the volume of the cylinder drum.
Corrugations proceeding in the direction of the diameter and in the form of low metal sheets the free upper edges of which proceed in a manner following the direction of rotation, can be attached to the internal side and non-perforated portion of the cylinder drum casing.
The pressing roller is supported by means of swivelling arms, the centers of gravity of which are located on the external housing of the device. It presses the sediment located on the filter belt, and the filter belt is conveyed along between the jointed belt conveyor and cylinder drum. The supply roller for the filter belt is supported within a roller body and, upon reaching a specific minimal diameter, activates a switching device which indicates that the roller should be changed or switches the machine off.
Because the device of the present invention has been greatly simplified and is easy both to monitor and to maintain, the actual housing of the device comprises only sidewalls which are held in their positions relative to one another by means of the various support axes for the continuous jointed belt conveyor and for the supply roller of the filter belt.
The lower portion of the housing defined by the two sidewalls is formed into a trough into which the purified wastes then flow as soon as the edge of a cylinder drum casing part bounding one opening of the cylinder drum appears below the fluid level set in the cylinder drum. The fluid then flows against the direction of rotation of the cylinder drum, over the dam-like end of the cylinder drum casing part, into the trough and, finally, into a depression which serves as a collecting container for the purified wastes, and from which it is pumped out.
Because the cylinder drum serves both as a reaction container as well as a sedimentation container, the precipitate can settle to the bottom on the uninterrupted portion of the cylinder drum casing. Also, because the cylinder drum rotates slowly, and preferably in stages in such a way that the cylinder drum stands still between every cycle, sediment can precipitate over a long period of time and deposit, and then be moved by the purified wastes flowing out onto the filter belt lying free in the open within the opening of the cylinder drum casing. The purified wastes flow through the filter belt where fine particles are filtered out, and reach the trough which is positioned underneath the cylinder drum and through which the lower section of the jointed belt conveyor is also conducted.
Drive motors are located next to and on one side of the device. The drive motors are for the continuous jointed belt conveyor, as well as for the dosing device by which the chemical mixture is moved into the interior of the cylinder drum for the processing of the wastes. The sidewalls of the cylinder drum have larger openings so that the installation of the mixing device and of the level switch is facilitated. The water to be purified is also conducted in a suitable manner through these openings and into the interior of the cylinder drum.
The device is constructed so that the weights on both sides of the device are equalized or approximately equalized. The weight of the two motors with the gearing approximately corresponds to the weight of the dosing device with the supply of chemical mixture for the processing of the fluid. Both motors are adjustable so that, as previously mentioned, the rotational speed can be varied, as can the quantity of the chemicals which are conveyed to the wastes to be purified.
The invention will now be described in greater detail by means of an example of an embodiment of execution, which is depicted in the attached drawings.